It is not legal in the regs, nothing is legal in the regs, the regs have no legal status.
It can comply with regulations if the requirements of the regulations are met, if they are not then it does not comply.
Use the adiabatic equation to calculate the required CSA of a steel CPC and then compare that to the actual CPC, this will tell you whether it is the right size or not.
Then measure the Zs using a high current test and this will tell you whether that complies or not and give an indication that all connections are sound.
ideally you would use a ductor type high current milliohm meter to confirm the soundness of the connections but they aren't so commonly available to us humble electricians any more
Sent from my iPad using Tapatalk